added a simple register example

examples/register/read_register.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+
+# Copyright 2013-present Barefoot Networks, Inc. 
+# 
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+# 
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+THIS_DIR=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
+
+source $THIS_DIR/../env.sh
+
+CLI_PATH=$BMV2_PATH/targets/simple_switch/sswitch_CLI
+
+if [ $# -lt 1 ]; then
+    echo "Please specify register index"
+    exit 1
+fi
+index=$1
+
+echo "register_read my_register $index" | $CLI_PATH register.json